Device for Selectively Dispensing Limestone for a Regenerating Oven and Process for Selectively Loading Limestone in a Regenerating Oven Using Such Device

ABSTRACT

A selective dispensing device ( 1 ) is disclosed for limestone in vats ( 5   a,    5   b ) of a regenerating oven adapted to arrange limestone with greater sizes next to an external wall ( 7   a,    7   b ) of the vats ( 5   a,    5   b ) and limestone with smaller sizes next to an internal wall ( 8   a,    8   b ) of the vats ( 5   a,    5   b ), comprising at least one mobile bulkhead ( 11 ) connected to a drive shaft ( 13 ) rotating around a rotation axis (X), such rotation being driven by an actuator system and the mobile bulkhead ( 11 ) being able to rotate around the rotation axis X to be alternatively inclined by a first angle (α) and by a second angle (β) with respect to reference plane (Z).

The present invention refers to a device for selectively dispensing limestone for regenerating ovens. The present invention further refers to a process for selectively loading limestone in a regenerating oven using such device.

As known, parallel-flow regenerating ovens for manufacturing lime from limestone are composed of two vats, which are mutually interconnected through a connection channel.

Limestone is loaded in every vat and descends along the pre-heating area, in which regenerative heat exchange occurs in counter-current with fumes, passes the lances, which insert fuel and arrives to the baking/calcining area. From here, it reaches the lime cooling area.

The oven operation allows the alternate combustion in every vat with a combustion cycle which is 8 to 12 minutes long.

During every alternate combustion cycle, fuel is entered into the vat under combustion through the lances, and burns in the combustion air, which is blown into the vat, releasing heat, which is partly absorbed by the limestone calcining. Simultaneously, cooling air is entered at the base of every vat in order to cool the lime. The cooling air of the vat under combustion, together with combustion gases and carbon dioxide released from the limestone when calcining, pass through the transverse interconnected channel, reaching the other vat at a temperature up to 1050° C., in which they are mixed with cooling air at the base and rise, thereby heating the limestone which can be found in the heating area.

In traditional ovens, however, combustion gases rise along the vat through the limestone by travelling, due to their own physical nature, along the short trajectory, namely the one flanking the internal wall of each vat, making the heating of crosses limestone irregular.

Object of the present invention is solving the above prior art problems, by providing a device for selectively dispensing limestone for regenerating ovens which allows loading each vat by dividing the limestone depending on its size or granulometric curve, in such a way as to create a lower-resistance path defined for the combustion fumes circuit.

Another object of the present invention is providing a process for selectively loading limestone in a regenerating oven using the selective dispensing device according to the present invention.

The above and other objects and advantages of the invention, as will appear from the following description, are reached with a device for selectively dispensing limestone for regenerating ovens as claimed in claim 1.

Moreover, the above and other objects and advantages of the invention are reached with a process for selectively loading limestone in a regenerating oven using the selective dispensing device as claimed in claim 8.

Preferred embodiments and non-trivial variations of the present invention are the subject matter of the dependent claims.

The present invention will be better described by some preferred embodiments thereof, provided as a non-limiting example, with reference to the enclosed drawings, in which:

FIGS. 1 a and 1 b show various longitudinal sections of vats of a regenerating oven schematically showing the modes for filling with limestone using the selective dispensing device according to the present invention;

FIG. 2 shows a front sectional view of a regenerating oven equipped with the device for selectively dispensing limestone according to the present invention;

FIG. 3 a and 3 b show a side sectional view of a vat of the oven in FIG. 2 in different operating positions; and

FIG. 4 shows another side sectional view of the vat of FIG. 3 a and 3 b along the sectional plan A-A.

With reference to FIG. 1 a and 1 b, and in particular to representations a, b, c, d which show the loading modes with limestone respectively of a first vat 5 a with a top view, of the first vat 5 a with side sectional view, of a second vat 5 b with top view, of the second vat 5 b with side sectional view, it is possible to note that the scope of the selective dispensing device 1 according to the present invention is allowing to load with limestone each vat of a regenerating oven creating a lower-resistance path to descending/ascending flow of combustion fumes towards the top of each vat, advantageously arranging the limestone with greater sizes 3 next to the external walls 7 a, 7 b (as shown in representations a, b, c, d of FIG. 1 b) and limestone with smaller sizes 4 next to the internal walls 8 a, 8 b (as shown in representations a, b, c, d of FIG. 1 a) of each vat 5 a, 5 b. In fact, since limestone with greater sizes has interstices with bigger sizes among the granules once having been loaded in the vat with respect to existing sizes among granules with smaller sizes, which are arranged more compactly one with respect to the others, fumes will find a lower-resistance path next to the external wall, consequently travelling, when rising towards the limestone, along a longer path, consequently releasing a greater amount of heat, and in a more homogeneous way.

In order to obtain the above described results, and with reference to FIG. 2, it is possible to provide each vat 5 a, 5 b, next to its own hood, with a selective dispensing device 1 for limestone according to the present invention, as will be described below.

To obtain a more efficient use of the selective dispensing device 1 according to the present invention, it would be preferable to previously provide an operation for separating limestone in order to divide it depending on granule sizes into at least one batch with greater sizes and one batch with smaller sizes. The oven, and in particular each vat 5 a, 5 b, is then loaded through the top 6 a, 6 b of each vat 5 a, 5 b by a loading system (not shown) comprising at least one first line for loading limestone with greater sizes and at least one second line for loading limestone with smaller sizes. Preferably, loading occurs in each vat 5 a, 5 b through an alternate supply from the first loading line and the second loading line.

With reference now further to FIG. 3 a, 3 b and 4, it is possible to note that the selective dispensing device 1 according to the present invention comprises at least one mobile bulkhead 11, connected to a drive shaft 13 rotating around a rotation axis X, such rotation being driven by an actuator system, mentioned below; in particular, the mobile bulkhead 11 can rotate around the rotation axis X in order to be alternatively inclined by a first angle α and by a second angle β with respect to a reference plane Z (inclined positions are shown dashed in FIG. 2), such plane being preferably vertical and passing by the rotation axis X.

In order to obtain the selective loading of limestone in each vat 5 a, 5 b, it is therefore enough to provide that, when the vat 5 a, 5 b is supplied by the first loading line, the actuator system takes care of inclining the mobile bulkhead 11 by the first angle a (as shown in FIG. 3 a) in such a way as to address and arrange the limestone with greater sizes against the external wall 7 a, 7 b of the vat 5 a, 5 b itself; when instead the vat 5 a, 5 b is supplied by the second loading line, the actuator system takes care of inclining the mobile bulkhead 11 by the second angle β (as shown in FIG. 3 b) in such a way as to address and arrange the limestone with smaller sizes against the internal wall 8 a, 8 b of the vat 5 a, 5 b itself.

Obviously, the absolute values of the first and second angle α, β can be adjusted depending on limestone sizes granulometry and their respective rest angle, in such a way as to guarantee the most efficient selective loading according to the present invention for each vat 5 a, 5 b.

Always with reference to FIG. 3 a and 3 b, it is possible to note that the actuator system comprises an actuating piston 14, such as a double-effect cylinder of the pneumatic, hydraulic or oleo-dynamic type, connected to a bracket 15 of the drive shaft 13 substantially perpendicular to the rotation axis X; in such a way, when the actuating piston 14 cylinder performs its stroke along a direction, the mobile bulkhead 11 is inclined by the first angle α, while when the actuating piston 14 cylinder performs its stroke along the opposite direction, the mobile bulkhead 11 is inclined by the second angle β. The actuator system can obviously further comprise drive and control means of the actuating piston 14 which, depending on which loading line is supplying each vat, impose the related correct inclination to the mobile bulkhead 11.

It would be preferable, due to obvious actuator system managing and operating reasons, that the absolute values of the first and the second angle were the same, namely |α|=|β|: in such case, the mobile bulkhead 11 will be alternatively inclined by an angle +α and −α with respect to the reference plane Z.

The previous description has been made with reference to the Figures considering the reference plane Z as substantially vertical: it is however clear that the above described statements can be wholly applied also in case a substantially horizontal reference plane is taken into account, though this latter one is technically less practical to realise, due to reduced spaces available inside the vats 5 a, 5 b for placing an horizontal mobile bulkhead.

The present invention further refers to a process for selectively loading limestone in a regenerating oven using the selective dispensing device according to the present invention; in particular, the inventive process comprises the steps of:

-   separating limestone in order to divide it, depending on granules     sizes, into at least one batch with greater sizes and one batch with     smaller sizes; -   inclining the mobile bulkhead 11 by the first angle α with respect     to the reference plane Z through the actuator system; -   supplying a top 6 a, 6 b of the vat 5 a, 5 b through the first line     for loading limestone with greater sizes; -   inclining the mobile bulkhead 11 by the second angle β with respect     to the reference plane Z through the actuator system; -   supplying the top 6 a, 6 b of the vat 5 a, 5 b through the second     line for loading limestone with smaller sizes; -   repeating the previous steps till the vats 5 a, 5 b have been     suitably filled with limestone. 

1. A selective dispensing device of limestone in vats of a regenerating oven adapted to arrange limestone with greater sizes next to an external wall of the vats and limestone with smaller sizes next to an internal wall of the vats, where the device comprises at least one mobile bulkhead connected to a drive shaft rotating around a rotation axis (X), the rotation being driven by an actuator system and the mobile bulkhead being able to rotate around the rotation axis (X) to be alternatively inclined by a first angle (α) and by a second angle (β) with respect to a reference plane (Z).
 2. The selective dispensing device of claim 1, where the reference plane (Z) is vertical and passing through the rotation axis (X).
 3. The selective dispensing device of claim 1, where the reference plane (Z) is horizontal and passing through the rotation axis (X).
 4. The selective dispensing device of claim 1, where |α|=|β|.
 5. The selective dispensing device of claim 1, where the actuator system comprises an actuating piston connected to a bracket of the drive shaft perpendicular to the rotation axis (X).
 6. The selective dispensing device of claim 1, where the actuator system comprises drive and control means for the actuating piston.
 7. The selective dispensing device of claim 1, where the device comprises a system for loading limestone from a top part of the vats comprising at least one first loading line of the limestone with greater sizes and at least one second loading line of the limestone with smaller sizes.
 8. A process for selectively loading limestone in a regenerating oven using the selective dispensing device of claim 1, where the process comprises the steps of: (a) separating the limestone in order to divide the limestone into at least one batch with greater sizes and at least one batch with smaller sizes; (b) inclining the mobile bulkhead by the first angle (α) with respect to the reference plane (Z) through the actuator system; (c) supplying the top part of the vat through the first loading line of the limestone with greater sizes; (d) inclining the mobile bulkhead by said the second angle (β) with respect to the reference plane (Z) through the actuator system; (e) supplying the top part of the vat through the second loading line of the limestone with smaller sizes; and (f) repeating the previous steps until the vats are filled with the limestone. 